Cinnamon is a spice which is obtained from the bark of a number of species of plants which belong to the genus Cinnamomum. Although a number of plants belong to this genus, one plant in particular is often known as ‘true’ cinnamon, and this called Cinnamomum verum, or Ceylon cinnamon. Cinnamon has long been used as a cooking ingredient and part of traditional medicine, and recently it has drawn a lot of attention from the medical industry because, as with many herbs/ spices, it has a unique profile of polyphenols. Of particular interest is a group of polyphenols called proanthocyanidins (PAC) which are also known as condensed tannins, because they have demonstrated hypoglycemic properties, and are thought to behave in a similar way to insulin in the body. This literature review will investigate the research conducted on cinnamon and its phenolic compounds, and determine its benefits on the human body.

Phenolic compounds in cinnamon

Cinnamon contains a variety of polyphenols, and the quantity in which they are found will vary depending on each species of plant as well as the environment in which they are grown, although ‘true’ (Ceylon) cinnamon is thought to have the highest concentrations. Typically, the phenolic composition in 1g of cinnamon is as follows:

Total polyphenols – 46mg

Total proanthocyanidins (PACs) – 23mg – 0.501mg of which are cinnamtannin b1 – 9.17ug of which are catechins – 0.553 of which are trans-cinamic acid (Diana M. Cheng et al. 2012)

Cinnamon contains the highest source of PACs. To put this into perspective an apple contains 0.01mg/g of PACs (Liwei Gu, 2004), and apple are one of the main dietary sources of PAC in the American diet. 1 gram of cinnamon contains almost 2300 times as much PAC as a gram of apple. As you can see from the above list, cinnamon will contain a variety of PACs, as the total amount of PACs is 23mg, and the most abundant PAC (cinnamtannin B1) which only accounts for 0.501mg of this. It is these PACs which are thought to offer cinnamon its beneficial properties, although the other polyphenols are also likely to contribute to these benefits too.

Investigations into the health benefits of cinnamon

– Diabetes

Most research on cinnamon and its phenolic compounds (particularly cinnamtannin B1) have been on its potential to help the body regulate blood sugar. A review in 2012 of 16 studies on cinnamon and its possible ability to help regulate blood sugar which was published in the Diabetes Medicine Journal concluded that cinnamon demonstrated the ability prevent glucose absorption and potentiated insulin receptor activity (P. Ranasinghe et al 2012). This study used animals/ human cells, and showed there is a clear indication that cinnamon can interact with insulin receptors in a beneficial manner, particularly with regard to protecting against diabetes. Reducing the amount of glucose absorbed reduces the sharp insulin spike caused by consuming large amount of sugar which increases the risk of diabetes, and by potentiating insulin reception activity it reduces the stress on the pancreas to produce large amounts of insulin, which prevents the destruction of the beta cells.

In 2013 another review was conducted by the Cochrane group which reviewed 599 records of studies on cinnamons impact on the risk of type 2 diabetes. Of these records, only 15 actually had papers published, and were deemed complete enough to be included in the review (Leach MJ et al 2012). The review concluded that the species Cinnamomum cassia in “tablet or capsule form, at a dose of 0.5 to 6 g daily for a period of four to 16 weeks, is no more effective than placebo or control intervention.” The review does say that the studies were all at risk of bias, and so more research is needed, especially with regards to other species such as Ceylon (true) cinnamon as results are likely to be different. Although a review by the Cochrane group conclude that more research is needed, it does state that there is likely to be different results for the various species of cinnamon, and only Cinnamomum cassia appeared to be ineffective. The Cochrane group have said that glucose regulation by cinnamon is certainly a possibility, but until more reliable studies are conducted, there is just not enough research to make conclusive claims about the extent of the benefit.

Studies outside of the above reviews have repeatedly concluded that cinnamon can significantly improve blood glucose management (Ting Lu, 2012) (Richard A. Anderson, 2008). Although these studies have been conducted in humans, they are only small trials, and so their results will be more easily swayed by anomalies and uncontrollable variables.

Although there is much more research needed to determine the extent of the benefit of consuming cinnamon to help protect against diabetes and help control blood sugar, there is evidence to suggest that cinnamon will offer some protection against diabetes, and the Cochrane group have not ruled out the possibility of its benefits, but agree more research is needed.

– Antioxidant potential

Many phenolic compounds are well recognised for their antioxidant capacity, and this has been confirmed in many studies. The phenolics in cinnamon unsurprisingly have repeatedly been shown to posses antioxidant properties (Bin Shan, 2005) (G. K. Jayaprakasha, 2006). Due to the abundance and type of phenolics found in cinnamon, the antioxidant capacity of cinnamon is much greater than other herbs and spices (Lan Su, 2007). In comparison to vitamin C, which is a powerful diprotic antioxidant, cinnamon has demonstrated an antioxidant capacity which is 460% more powerful than that of vitamin C |(Muchuweti, M et al, 2007). This clearly demonstrates that the phenolic components of cinnamon will offer the body protection against oxidative stress, which is associated with protective effects against a number of diseases increasing the risk of diabetes, cardiovascular disease and cancer. (R Blomhoff, 2005).

Negative effects of cinnamon

There has been no recorded negative effects of consuming cinnamon up to 6g, and above that value there has been no tests to determine ill effects. Consuming cinnamon is deemed safe, and even in large quantities is unlikely to pose a serious risk to health (although consumption above 6g/ day is not recommended).

Conclusion

Cinnamon is a rich source of a unique spectrum of polyphenols, in particular, cinnamon is high in a group of polyphenols called proanthocyanidins (PACs), which have been of particular interest to the health and medical communities. The most interesting benefits of cinnamon and its polyphenols is its ability to act upon insulin receptors, which can help protect against developing type 2 diabetes. With type 2 diabetes rising in many countries, this has stimulated a number of studies investigating the impact PACs can have on protecting against type 2 diabetes. Although the majority of current evidence does suggest that cinnamon can offer protection against type 2 diabetes, studies on this have only been small and subject to bias, so although research is promising, concrete conclusions can not be made on this benefit yet. In addition to the possible protective effects against type 2 diabetes, the polyphenols found in cinnamon are powerful antioxidants, and so are able to help protect the body against a range of diseases linked to oxidative stress, including cardiovascular disease and diabetes.

As there are no ill effects of consuming cinnamon, and only beneficial effects recorded, consumption of cinnamon will contribute to a healthy body, and can help protect against a number of diseases.